The sediment sampling on which the helicopter was engaged involved a series of flights, each of the order of
two to four minutes duration. Between individual flights the aircraft remained on the ground with the engine
running for the short period required for the rear seat passengers to disembark, collect sediment samples
and re-embark for the flight to the next selected location. The passenger in the left hand rear seat would then
signal, by tapping the pilot on the shoulder, that both rear seat occupants were strapped in and take off could
commence. Conditions in the area were hot and dry and at each take off and landing the rotor wash raised
targe quantities of dust.